Question

Calculati P=1+2+2la a 2 +.........+2la a 7

Answer 1

1+2+4+8+16+32+64+128=255
=> P=255

Answer 2

Sau ...
aplicam formula
1+2+2²+...+ $2^{n}=\frac{2^{n+1}-1}{2-1}$
P = $\frac{2^{7+1}-1}{2-1}=\frac{256-1}{1}=255$